Oven Providing Surge Mode Cleaning

ABSTRACT

A cleaning system for an oven having shelves which provide for distributed jets of heated air, allows water accumulation within the shelves during cleaning by reducing airflow through the shelf, and then provides rapid expulsion of the water in cohesive streams after accumulation to provide high inertial cleaning.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.17/205,723, filed Mar. 18, 2021, which is incorporated by referenceherein in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to food preparation ovens and inparticular to ovens having built-in water-cleaning systems.

Combination steam and convection ovens (“combi-ovens”) cook usingcombinations of convection and steam. In convection cooking, heated airis circulated rapidly through the cooking compartment to break upinsulating layers of air around the food, thereby increasing the rate ofheat transfer. Steam enhances the rate of heat transfer to the food as aresult of the high specific heat of water compared to dry air and canalso reduce water loss from the food. Combi-ovens are described, forexample, in U.S. Pat. Nos. 7,307,244 and 6,188,045 assigned to theassignee of the present invention and hereby incorporated by reference.

Combi-ovens may have provisions for cleaning by introducing water intothe cooking cavity together with a detergent. This water and detergentmay be heated and circulated by the oven fan and heater as a highvelocity, atomized mist.

Professional kitchens are often called upon to simultaneously prepare awide variety of dishes each one optimally being cooked for differentperiods of time, temperatures, and humidity. For this purpose, amulticavity oven has been developed having independent cooking chambersintroducing heated air through openings in divider shelves between thechambers. An upper divider shelf may deliver heated air downwardly onthe food while a lower divider shelf delivers deliver air upwardly. Airis distributed through the shelves by channels within the shelvescommunicating with a fan and heating system of the oven. Ovens of thiskind are commercially available from Alto-Shaam, Inc. of MenomoneeFalls, Wisconsin, under the Vector trademark and subject to multiplepending patent applications including 2019/0056118; 2020/0041135;2017/0211819; and U.S. application Ser. No. 17/078,711 filed Oct. 23,2020, all hereby incorporated by reference.

SUMMARY OF THE INVENTION

The present inventors have recognized that the atomized water and steamproduced in conventional oven cleaning systems may be inadequate forremoving stubborn oven residue and clearing air channels in the dividershelves of multicavity ovens. The present invention accordinglyintroduces a surge cleaning system in which the oven fans are modulatedto first allow an accumulation of water in the lower divider shelf andthen to rapidly discharge this water in one or more substantiallyunbroken streams, the streams carrying debris from the shelves andproviding a consolidated inertial impact against oven walls that canpromote deep cleaning. Counter intuitively, the inventors haverecognized that intermittent operation of the fans during cleaning canpromote improved cleaning results.

Specifically, the present invention provides a multi-cavity oven havinga housing holding a cooking volume surrounded by insulated outer wallsand at least one door that may open and close to provide access to thecooking volume. A set of shelves divides the cooking volume into cookingcavities, the shelves having air channels each leading from an air inletto upwardly or downwardly directed airstream openings into adjacentcavities. At least one fan provides air through the air channels intothe air inlets, and a water inlet communicates with a water valve tointroduce water into the cooking cavities. A controller controls theoven to provide a first and second cleaning state. In the first state,the fan operates below a predetermined airflow rate to allow water fromthe water inlet to drain backward into and accumulate in the airchannels and in the second state, the fan operates above thepredetermined airflow volume to rapidly expel accumulated water from theair channel through the airstream openings in at least one stream.

It is thus one feature of at least one embodiment of the invention toprovide improved cleaning over atomized water and air by allowing wateraccumulation that can provide for high inertial impact against ovensurfaces and that can help carry material and debris out of the airchannels of the shelves.

The air may enter the rear of the shelf opposite the door so thatmomentum of the water moving through the air channels before dischargethrough the airstream openings directs at least one stream toward thedoor. The door may provide a glass panel.

It is thus a feature of at least one embodiment of the invention toprovide improved cleaning of the door allowing better viewing of foodduring cooking and improved oven aesthetics after cleaning.

The shelves may include a set of airstream openings spaced along twodifferent perpendicular dimensions of the shelves each providing astream of water.

It is thus a feature of at least one embodiment of the invention toprovide for multiple focused streams of water that may have highervelocity.

The oven may further include a set of drains leading from the cavitiesand wherein the valve controls the water inlet to provide a greater flowof water into the cavity than a flow of water out of the cavity throughthe drains to allow accumulation of water in the air channels.

It is thus a feature of at least one embodiment of the invention toprovide a system that can allow for water accumulation while observingthe necessity of draining water after the cleaning process.

The oven may include a heater operating to heat the water circulating inthe cavity through action of the fan. It is thus a feature of at leastone embodiment of the invention to provide both high inertial and heatedwater streams for improved cleaning.

In a second embodiment of the invention, the oven may include a steamgenerator for generating steam for introduction into the cooking volume.In this embodiment the controller may (a) open the water valve to allowwater to flow in through the water inlet while operating the circulatingfan to circulate water and a detergent material through the cookingvolume; (b) allow a draining of detergent and water from the cookingvolume; and (c) introduce steam into the cooking volume to dissipateaccumulated detergent foam.

It is thus a feature of at least one embodiment of the invention toeliminate residual bits of detergent foam which can remain in the ovencavities, generated by the high degree of air turbulence and yetfloating on rather than flowing with discharged water. The inventorshave determined that high temperature steam can disrupt the structure ofsuch foam without the need for additional rinse cycles.

The controller may further operate to include a step before step (a) ofintroducing steam into the cooking volume to soften accumulated grease.

It is thus a feature of at least one embodiment of the invention to makeuse of steam available in ovens of this kind both for initial and finalcleaning steps.

The controller may further operate to provide a rinse cycle after step(b) in which additional water is introduced through the water inlet intothe cooking volume and circulated by the fan and then allowed to drainfrom the cooking volume, and a rinse cycle after step (c) in whichadditional water is introduced through the water inlet into the cookingvolume and circulated by the fan and then allowed to drain from thecooking volume.

It is thus a feature of at least one embodiment of the invention tocollapse detergent foam so that it can be successfully rinsed out of theoven with a second rinse cycle thus allowing optimization of rinsewater.

In yet another embodiment of the invention, the oven may provide anexhaust conduit associated with each chamber and having an exhaustconduit valve leading between each chamber and air outside of thehousing. The controller communicates with the exhaust conduit valves tocontrol the exhaust conduit valves during the cooking mode toindependently control exhaust from each chamber according to separatecooking schedules and to control the exhaust conduit valves during acleaning mode to open the exhaust conduit valves and water inlet valveto allow circulation of cleaning water by the fan through the cavitiesand at least a portion of the exhaust conduits.

It is thus a feature of at least one embodiment of the invention toprovide improved cleaning of exhaust channels used for rapid airexchange in ovens of this kind. The inventors have determined thatopening the valves reduces an effective dead space of air trapped in theexhaust channels that prevents proper cleaning.

The exhaust conduit valve may be displaced from a respective chamber bya portion of the exhaust conduit.

It is thus a feature of at least one embodiment of the invention toallow proper cleaning of an exhaust channel when the exhaust conduitvalve is positioned away from the cooking chamber for protection againstheat and direct contamination.

The portion of the exhaust conduit before the exhaust conduit valve mayexit downwardly from the cooking cavity.

It is thus a feature of at least one embodiment of the invention toprevent minor amounts of contamination in the exhaust conduit frombreaking off and falling into subsequent food in preparation.

Each exhaust conduit may provide a separate channel from a respectivechamber to outside air.

It is thus a feature of at least one embodiment of the invention toprevent intercommunication between the cooking chambers through theexhaust conduits that could provide flavor transfer during differentcooking cycles in different cavities where one cavity is in anoverpressure state and one cavity is in a relative under pressure state.

The exhaust conduits may exit to outside air at openings separated fromeach other by a divider wall extending along a direction of airflow fromthe conduits from the openings and beyond the openings.

It is thus a feature of at least one embodiment of the invention toallow the exhaust conduits to exit at a common location, for example,removed from the oven user, without risking cross-contamination in theatmospheres of the chambers. The divider plate provides increasedseparation between the exhaust conduits while exposing them to theoutside air for diffusion.

These particular objects and advantages may apply to only someembodiments falling within the claims and thus do not define the scopeof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a four-cavity oven according to oneembodiment of the present invention showing an expanded detail of ashelf made of separate upper and lower plenums individually removablethrough the open door of the oven;

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1 showingthe segregated internal air channels in the shelf such as may conductdifferent temperatures of air while maintaining thermal separationbetween the cavities by active insulation and other techniques;

FIG. 3 is a simplified block diagram of the air delivery system andwater control valves used for steam generation and cleaning feedbackcontrol;

FIG. 4 is a fragmentary elevational schematic cross-section throughmultiple cavities of FIG. 1 showing the airflow from a fan and heatersystem into the cavities via the shelves dividing the cavities;

FIG. 5 is an planar schematic cross-section through one cavity of theoven of FIG. 1 showing the fan and steam-generating system together withvalving and a drain system for managing cleaning water and air intakeand exhaust conduits leading to outside air;

FIG. 6 is a fragmentary cross-sectional view similar to that of FIG. 2showing an accumulation stage of a cleaning cycle where a charge ofwater is allowed to collect in a lower divider shelf;

FIG. 7 is a figure similar to that of FIG. 6 showing a rapid dischargeof the collected water in a second surge stage of the cleaning cycle ina set of non-atomized sheets;

FIG. 8 is a timing diagram of a program executed by the controller toprovide the surge cleaning of FIGS. 6 and 7 and providing a foamreduction treatment collapsing residual detergent foam;

FIG. 9 is a side elevational view of the oven of FIG. 1 showing anarrangement of exhaust conduits and valving to improve cleaning of theconduits and to prevent inter-cavity transfer of odors;

FIG. 10 is an exploded perspective fragmentary view of a chimney holdingthe exhaust conduits of FIG. 9 in separation for communication withoutside air; and

FIG. 11 is a figure similar to FIG. 10 in assembled form.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1 , a multi-zone, combi-oven 10 may provide for ahousing 12 having upstanding insulated left and right outer sidewalls 14a and 14 b and an upstanding outer insulated rear wall 14 c extendingbetween and joining opposed, generally horizontal insulated outer upperwalls 14 d and 14 e. The walls 14 enclose a volume 16 opening toward thefront and which may be covered by hinged door 18 when the door 18 is ina closed position as is generally understood in the art. The housing 12may be supported on one or more legs 21 extending downwardly from abottom surface of the bottom wall 14 e.

The cooking volume 16 may be divided into multiple cooking cavities 20a-d. Although four cooking cavities are shown, the inventioncontemplates a range from 2 to 6 cooking cavities 20 in vertical, spacedseparation. Each of the cooking cavities 20 is separated by a shelf 22a-c with shelf 22 a separating cavities 20 a and 20 b, shelf 22 bseparating cavities 20 b and 20 c and shelf 22 c separating cavities 20c and 20 d.

Referring also to FIG. 2 , each shelf 22 may be made up of a separateupper and lower generally rectangular plenum 24 a and 24 b fittinghorizontally in the cooking volume 16 with plenum 24 a facing an uppercavity 20 and plenum 24 b facing a lower cavity 20. A single upperplenum 24 a forms the bottom of the lowermost cavity 20 d and a singlelower plenum 24 b forms the upper wall of the uppermost cavity 20 a.

An outer surface of each plenum 24 provides a horizontally extending airdistribution plate 28 having a set of airstream openings 30 distributedover its area to provide for substantially even airflow therethrough. Inone embodiment, the airstream openings 30 in the air distribution plate28 may provide a series of holes 31 joined by slots 33 extending inmultiple rows from the left to the right side of the cavities 20 asdescribed in U.S. patent application Ser. No. 15/224,319 referencedabove. Generally, a width of the slots 33 will be less than 0.05 inchesand preferably less than 0.1 inches to reduce pressure loss in thechannel 34 that could result from high slot area. The holes 31 are muchlarger than the slot 33 and maybe circular and may have a diameterranging from 0.3 inches to 0.6 inches to provide airstreams that helpshepherd the air from the slots 33 while also minimizing loss of airpressure. Slot lengths may vary between 1 to 2 inches and are preferablyapproximately 1.6 inches. The air distribution plate 28 is a thin sheetof metal, for example, stainless steel, with a thickness less than ⅛inch and typically less than 1/16 inch, such as may be easily formedusing laser cutting techniques.

Air enters through sidewalls of each of the plenums 24 a and 24 b at airinlets 32 a and 32 b, respectively, from corresponding outlets at therear of each cavity. These air inlets 32 may be as little as 1½ inchestall and preferably less than one inch tall. From the air inlets 32 aand 32 b, the air then passes through a horizontally extending channel34 defined by an inner surface of the air distribution plates 28 andinner surface of a focusing wall 36 opposite the air distribution plate28 about the channel 34. The focusing wall 36 has a maximum separationfrom the air distribution plate 28 at the air inlet 32 and then curvesinward toward the air distribution plate 28 as air conducted in thechannel 34 escapes through the airstream openings 30 and less channelheight is needed. This inward sloping of the focusing walls 36 for eachof the plenums 24 a and 24 b together provides an additional insulationzone 38 between the barrier walls 36 of the upper and lower plenums 24 aand 24 b, respectively, minimizing shelf height but maximizinginsulation value. The average separation of the barrier walls 36 may beapproximately one inch varying from contact between the barrier walls tonearly 2 inches in separation. The invention contemplates an averageseparation of at least one-quarter inch and preferably at least oneinch.

A peripheral wall 40 of each plenum 24 surrounds the air distributionplate 28 and the barrier wall 36 to corral air within the channel 34 inall directions except through the inlets 32 and the airstream openings30. Peripheral wall 40 also provides inwardly horizontally extendingtabs 43 which may support a wire rack 45 at a separation ofapproximately ¼ inch and at least ⅛ inch above the upper extent of theair distribution plate 28 of the upper plenum 24 a. In one embodimentthe wire rack 45 may be supported by more than one inch above the airdistribution plate 28 and desirably more than 1.5 inches above the airdistribution plate either through the use of a special wire rack 45 orextender tabs 43 (not shown). In this way, a cooking sheet or pan set ontop of the shelf 22 rests on the wire rack 45 and does not block theairstream openings 30. In a preferred embodiment, a separation 44 (shownin FIGS. 1 and 4 ) between the uppermost extent of the airstreamopenings 30 of the air distribution plate 28 of the upper plenum 24 aand the lowermost extent of the airstream openings 30 of the airdistribution plate 28 of the lower plenum 24 b will be less than fourinches, preferably less than three inches and desirably less than twoinches providing an extremely compact shelf maximizing cavity space andminimizing total height. The cavities 20 (shown in FIGS. 1 and 4 ) willhave a nominal height 42 between four and nine inches and preferablyfive inches or more defined by the distance between air distributionplates 28 bounding the upper and lower extent of the cavity 20. In onenonlimiting example, each cavity may add a height of about seven inchesto the oven so that three cavities may have a height of no more than 23inches or at least no more than 25 inches, and four cavities may have anominal height of 30 inches and no more than 35 inches.

Generally the shelves 22 may be constructed entirely of stainless steelfor durability and ease of cleaning, and although the inventioncontemplates that thin insulating materials may also be incorporatedinto the shelves 22 in some embodiments, the invention contemplates thatno nonmetallic shelf construction materials are required. The barrierwalls 36 may be held within each plenum 24 with a “floating mounting”allowing sliding of the barrier walls 36 with respect to the otherstructures of the plenums 24, for example, by creating a sliding fitbetween these components augmented by a natural flexure of the metal ofthe barrier walls 36 providing a light pressure between the barrierwalls 36 and the ribs 29 and inwardly extending lips of the peripheralwalls 40.

Referring now to FIG. 3 each of the cavities 20 may be associated with atemperature sensor 41 communicating with a controller 47, for example,being a microcontroller having one or more processor 48 executingprograms and communicating with an associated memory 49, holding anoperating program 51 and various recipe schedules 76. The temperaturesensors 41 may be thermistors, resistive temperature sensors, or thelike.

Each cavity 20 may also be associated with an airflow system 50comprising a heater system, fan motor, and variable speed motorcontroller so that the controller 47 may independently control theairflow circulating through each cavity 20 through a continuous rangeand may control the temperature of that air through a continuous rangeof temperatures. The heater system may be, for example, an electricresistance heater such as a “cal” rod controlled by a solid-state relayor may be a heat exchanger of an electrically controllable gas burnersystem.

Optionally, each cavity 20 may have an electrically controllable washwater valve 52 communicating with a common water supply 54 so that waterfor cleaning may be introduced into the cavity by a signal to thecontrollable wash water valve 52 from the controller 47. Additionalsteam control valve 53 may be operated to allow water to be introducedto the heating units of the airflow system 50 as will be discussed belowto allow independent control of moisture according to a cookingschedule. Mechanisms for the introduction of controlled moisture into anoven cavity 20 suitable for the present invention are described, forexample, in U.S. Pat. Nos. 9,375,021; 7,307,244; 7,282,674; and6,188,045 assigned to the assignee of the present application and herebyincorporated by reference.

The controller 47 may also receive a signal from a door switch 56 (suchas a limit switch or proximity switch) and may provide for input andoutput to an oven user through a user interface 58 such as a touchscreen, graphic display, membrane switch or the like such as are wellknown in the art. A data connector 60 may communicate with thecontroller 47 to allow for the readily uploading of cooking schedules 76over the Internet or by transfer from a portable storage device or thelike.

One or more of the cavities 20 may also include a smoker 61, forexample, providing a compartment that may hold woodchips or the like tobe heated by an electric element controlled by the controller 47 throughcorresponding solid-state relays. The construction of a smoker 61suitable for the present invention is described, for example, in U.S.Pat. Nos. 7,755,005; 7,317,173; and 7,157,668 each assigned to theassignee of the present invention and hereby incorporated by reference.

Referring now to FIG. 4 , the airflow system 50 of each cavity 20(indicated generally by separating dotted lines) may include a separatefan 62 independently controlled by a variable speed motor and motordrive 64. The fan 62 may be, for example, a squirrel cage fan and themotor a DC synchronous motor driven by a solid-state motor controller ofa type known in the art. The use of separate fans 62 permits fullsegregation of the airflows within each cavity 20. The use of a separatemotor and motor drive 64 allows independent airspeed control of the airin each cavity 20.

The airflow system 50 may also include a heater 66 and the air from eachfan 62 may pass through a heater 66 to be received by a bifurcatedmanifold 68 which separates the heated airstream into an upper airstream70 and lower airstream 74. The upper airstream 70 passes into thechannel 34 (shown in FIG. 2 ) of a lower plenum 24 b of an upper shelf22 defining an upper wall of the cavity 20 and then exits from thechannel 34 as a set of downwardly directed airstreams 72 a from each ofthe airstream openings 30 (shown in FIG. 2 ) distributed over the lowerarea of the plenum 24 b. The lower airstream 74 passes into the upperchannel 34 of upper plenum 24 a of a lower shelf 22 defining a lowerwall of the cavity 20 to exit from the channel 34 as a set of upwardlydirected airstreams 72 b from each of the airstream openings 30 (shownin FIG. 2 ) distributed over the upper area of the plenum 24 a.

The bifurcated manifold 68 may be designed to provide substantiallygreater airflow in the upper airstream 70 than the airflow of the lowerairstream 74, for example, by constrictions or orientation of thebranches of the bifurcated manifold 68 with respect to the naturalcyclic flow of the fan. In one example, the air may be split so that 53to 60 percent of the heated air is allocated to the lower shelf sendingair upward, and 40 to 57 percent of the heated air is allocated to theupper plenum pulling downward as described in U.S. patent applicationSer. No. 15/016,093 cited above.

This arrangement of fans, airflow system 50 and bifurcated manifold 68is duplicated for each cavity 20. In the uppermost cavity 20 a only asingle lower plenum 24 b is provided at the top of that cavity 20 a andin the lowermost cavity 20 d only a single upper plenum 24 a isprovided, each being effectively one half of shelf 22.

Referring now to FIG. 5 , in one embodiment, the fan 62 may be acentrifugal fan having a squirrel cage impeller mounted for rotationabout a horizontal axis 80 extending from the right to left wall of theoven 10 with the fan 62 centered with respect to the volume of thecavity 20. A steam generator 82, also positioned rearward from eachcavity 20 and leftward from the fan 62 (for example), provides a waterinjector 84 providing a conduit and nozzle directing a stream of wateror water droplets onto a rotating spinner 86. The spinner 86 may bemounted for rotation, independent of rotation fan 62, driven by aspeed-controlled motor 88, or may make use of motor 64 with appropriatelinkage.

The water injector 84 may disperse freshwater onto the rotating spinner86 to break up the water and emit a fine spray of water that is heatedby a helical heater tube of heater 66 surrounding the spinner 86. Waterto the water injector 84 may be controlled by an electronicallycontrolled wash water valve 52. In this way, the convection fanspeed-controlled motor 64 and the spinner speed-controlled motor 88 areindependently controlled to provide separate control of a heating of theoven cavity 20 and steam generation of the oven cavity 20.

Referring still to FIG. 5 , air from the fan 62 as heated by the heater66 may enter into the cavity 20 to heat contained food and then be drawnthrough a side vent 90 into a return duct 92 to again pass by the heater66. The size of the side vent 90 is such as to provide a slightconstriction producing a low pressure in the return duct which maycommunicate with a fresh air conduit 94, either directly or optionallycontrolled by valve 96, providing air inlet from outside of the oven.Valve 96 may be controlled by the controller 47.

Likewise, the cavity 20 will be at slightly higher pressure because ofthe size of the side vent 90 and may communicate with an exhaust conduit98 controlled by valve 100 through controller 47 providing an exhaust ofair and steam from the cavity 20 to the outside air as will be discussedbelow.

As noted above, wash water can be introduced into the cavity 20, forexample, through a spray nozzle in the cavity 20 or in the bifurcatedmanifold 68 or both. A system of drains 102 allows excess water to bedrained into a holding reservoir 104 into which a detergent material 106may be placed for cleaning. This reservoir 104 may provide water througha pump (not shown) to the wash water valve 52 for recycling cleaningwater and may provide for a drain 108 and freshwater make up valve 110leading to a freshwater supply as is generally understood in the art.

Referring now to FIG. 8 , the program 51 of the controller 47 (shown inFIG. 4 ) implements a cleaning sequence beginning at a stage 120, forexample, as initiated by the user entering information through interface58 (shown in FIG. 8 ). At this time program 51 may communicate to theuser that detergent material should be added to the reservoir 104 orplaced within each of the cavities 20 by means of display of theinterface 58 shown in FIG. 3 .

Once detergent has been added and the door is closed, as indicated bydoor switch 56 (shown in FIG. 3 ), the heater 66 may be activated andsteam water valve 53 opened to begin the production of steam generationas indicated during stage 122 a. At this time, the wash water valves 52are closed and the exhaust conduit valves 100 (shown in FIG. 5 ) areopened to encourage cleaning steam to enter and soften material in theconduits 98. The fan motor 64 is operated to assist in steam dispersion.

At the next stage 122 b, wash water valves 52 are opened and steam watervalve 53 closed while maintaining activation of the heater 66 so thatheated water is introduced into each cavity 20 and circulated by thehigh-speed air from the fan 62. This process produces a spray ofdetergent-infused, heated and atomized water coating all cleanablesurfaces of the oven interior.

Referring now also to FIG. 6 , at the next stage 122 c, surge cleaningbegins and the fan 62 is turned off or lowered in speed so that water124 introduced through wash water valves 52 and heated by heater 66drains backwards into the upper plenums 24 through jet openings 30 tosubstantially fill the air channel 34. In this regard the drains 102 maybe sized or valved to allow sufficient water accumulation so that atleast 25% of the air channel 34 is filled and preferably there is asmall amount of standing water over the openings 30.

At the next stage 122, the fan 62 may be turned on again quickly to highspeed producing a sudden pressurized flow 126 of air into the channels34 as shown in FIG. 7 . This ejects multiple continuous streams or slugs130 of water and/or suds from the openings 30 which, in contrast to theatomized heated water, provide a scouring flow emptying channels 34 ofdebris and a contiguous mass of water providing high inertial impact tothe surfaces of the oven. In this tsunami type flow, softened grease andthe like may be removed. The momentum of the water within the airchannel 34 prior to exiting encourages the cohesive streams of water 130toward the glass 93 on the inner surface of the of the door 18 providingimproved cleaning of this highly visible surface. In one embodiment, thestreams of water 103 will have a contiguous extent from the openings 30upward by one or more inches without substantial dispersion.

The steps of stages 122 c and 122 d may have a duration of approximatelyone minute and may be repeated multiple times, alternating between theaccumulation of FIG. 6 and stage 122 c and the rapid expulsion of slugsof water in a surge as shown in FIG. 7 per stage 122 d.

At a next stage 122 e, the wash water valve 52 and heater 66 are turnedoff and water is allowed to drain. The fan 62 is activated to help inthis process.

After a suitable draining time, at stage 122 f, a rinse is performed inwhich the wash water valve 52 is again activated optionally with theheater 66 and the fan 62 followed by second drain stage 122 e.

At the conclusion of this draining, there may be bits of detergent foamremaining in the cavity 20 representing an extremely small amount ofpersistent material. At a successive foam elimination stage 122, steamis again activated by turning on steam water valves 53, heater 66, andmotor 88 without wash water through wash water valve 52 but with the fan62 on to disperse the steam. The hot steam quickly expands the containedair pockets in any detergent foam structure breaking down the foam. Thissteam reduction step of stage 122 a may be followed by an optionaladditional rinsing stage 122 f and then a drying stage 122 g where thefan 62 and heater 66 are activated without water or steam.

Referring now to FIG. 9 , during the cleaning process, the valves 100 ofthe exhaust conduits 98 may be opened as noted to encourage steam andcleaning solution into the proximate portions of the exhaust conduits 98to clean cooking grease and the like from these portions which may haveentered during exhaust cycles to be cooled by these conduit walls andcondensed thereon. In one embodiment, the proximate portions of theexhaust conduits 98 may be angled downward from their connection to thecavities 20 so that any material not cleaned from the exhaust conduits98 does not subsequently fall into the cavity 20, for example, duringsubsequent heating when the material may possibly crack or flake off.After exiting at a downward angle, the exhaust conduits 98 may angleupward and be collected together through a chimney 160 to exit to theoutside air 163. The upward bend of the exhaust conduits 98 may includewater drains or the like passing to reservoir 104 if necessary.

Referring now to FIGS. 10 and 11 , as noted multiple exhaust conduits 98a-98 c may be collected together within a tubular chimney 160 to beconducted to the outside air 162. By collecting the exhaust conduits 98in this manner, heated steam or the like exhausted from the cavities 20may be safely directed away from users of the oven 10 to a singlelocation. However it is important that there not be a possiblecross-contamination path out of one exhaust conduit 98, for example,from a cavity 20 cooking with steam at overpressure, to a second cavity20 that, for example, might be cooling. In such cross-contaminationundesirable orders and flavors can be transferred between foods beingcooked in different cavities 20. Accordingly a divider plate 164 may beprovided at the end of the chimney 160 separating each of the openings166 of the exhaust conduits 98 from each other and extending for adiffusion distance of at least 1 inch and desirably at least 2 inchesalong axes 174 defining the direction of discharge of air from theexhaust conduits 98. In this diffusion distance 170 beyond the upperedge 172 of the chimney 160, flow between exhaust conduits 98 is blockedin favor of diffusion into the outside air. In this respect the dividerplate 164 may provide a simple set of divider walls extending radiallyat equal angles about the center of the chimney 160 to its periphery,the number of walls equal in number to the number of cavities 20 andpositioned between each distal end of an exhaust conduit 98.

As used herein the term fan is meant to include all motor driven devicesfor moving air including blowers fans and the like. Certain terminologyis used herein for purposes of reference only, and thus is not intendedto be limiting. For example, terms such as “upper”, “lower”, “above”,and “below” refer to directions in the drawings to which reference ismade. Terms such as “front”, “back”, “rear”, “bottom” and “side”,describe the orientation of portions of the component within aconsistent but arbitrary frame of reference which is made clear byreference to the text and the associated drawings describing thecomponent under discussion. Such terminology may include the wordsspecifically mentioned above, derivatives thereof, and words of similarimport. Similarly, the terms “first”, “second” and other such numericalterms referring to structures do not imply a sequence or order unlessclearly indicated by the context.

When introducing elements or features of the present disclosure and theexemplary embodiments, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of such elements orfeatures. The terms “comprising”, “including” and “having” are intendedto be inclusive and mean that there may be additional elements orfeatures other than those specifically noted. It is further to beunderstood that the method steps, processes, and operations describedherein are not to be construed as necessarily requiring theirperformance in the particular order discussed or illustrated, unlessspecifically identified as an order of performance. It is also to beunderstood that additional or alternative steps may be employed.

References to “a controller” and “a processor” or “the microcontroller”and “the processor,” can be understood to include one or moremicroprocessors that can communicate in a stand-alone and/or adistributed environment(s), and can thus be configured to communicatevia wired or wireless communications with other processors, where suchone or more processor can be configured to operate on one or moreprocessor-controlled devices that can be similar or different devices.Furthermore, references to memory, unless otherwise specified, caninclude one or more processor-readable and accessible memory elementsand/or components that can be internal to the processor-controlleddevice, external to the processor-controlled device, and can be accessedvia a wired or wireless network.

It is specifically intended that the present invention not be limited tothe embodiments and illustrations contained herein and the claims shouldbe understood to include modified forms of those embodiments includingportions of the embodiments and combinations of elements of differentembodiments as come within the scope of the following claims. All of thepublications described herein, including patents and non-patentpublications, are hereby incorporated herein by reference in theirentireties.

To aid the Patent Office and any readers of any patent issued on thisapplication in interpreting the claims appended hereto, applicants wishto note that they do not intend any of the appended claims or claimelements to invoke 35 U.S.C. 112(f) unless the words “means for” or“step for” are explicitly used in the particular claim.

What we claim is:
 1. An oven comprising: a housing providing a cookingvolume surrounded by insulated outer walls and at least one door thatmay open and close to provide access to the cooking volume; a waterinlet communicating with a water valve to introduce cleaning water intothe cooking volume; a drain for discharging cleaning water from thecooking volume; at least one fan for circulating air and water throughthe cooking volume; a steam generator for generating steam forintroduction into the cooking volume; and a controller communicatingwith the water valve, the fan, and the steam generator to provide acleaning cycle including the steps of: (a) opening the water valve toallow water to flow in through the water inlet while operating the fanto circulate water and a detergent material through the cooking volume;(b) allowing a draining of detergent and water from the cooking volume;and (c) introducing steam into the cooking volume to dissipateaccumulated detergent foam.
 2. The oven of claim 1 wherein thecontroller further operates to include a step before step (a) ofintroducing steam into the cooking volume to soften accumulated grease.3. The oven of claim 2 wherein the controller further operates toinclude a step of providing a rinse cycle after step (b) in whichadditional water is introduced through the water inlet into the cookingvolume and circulated by the fan and then allowed to drain from thecooking volume.
 4. The oven of claim 3 wherein the controller furtheroperates to include a step of providing a rinse cycle after step (c) inwhich additional water is introduced through the water inlet into thecooking volume and circulated by the fan and then allowed to drain fromthe cooking volume.
 5. The oven of claim 1 further including a heaterfor heating the cleaning water and where in the controller operates toactivate the heater during step (a).
 6. The oven of claim 1 furtherincluding a display and wherein the controller operates to instruct auser to introduce of detergent material into the cooking cavity beforestep (a).
 7. The oven of claim 1 further including a set of dividersdividing the cooking volume into at least two cavities; an exhaustconduit associated with each chamber having an exhaust conduit valve andleading between each chamber and air outside of the housing; and acontroller communicating with the heaters, fans, and exhaust conduitvalves to operate during a cooking mode to independently control heatingof each cavity and exhaust from each cavity according to separatecooking schedules and to operate during a cleaning mode to open theexhaust conduit valves and water inlet valve to allow circulation ofcleaning water by the fan through the cavities and at least a portion ofthe exhaust conduits.
 8. The multi-cavity oven of claim 7 wherein theexhaust conduit valve is displaced from a respective chamber by aportion of the exhaust conduit.
 9. The multi-cavity oven of claim 8wherein the portion of the exhaust conduit exits downwardly from thecooking cavity.
 10. The multi-cavity oven of claim 7 wherein eachexhaust conduit provides a separate channel from a respective chamber tooutside air.
 11. The multi-cavity oven of claim 7 wherein the exhaustconduits exit to outside air at openings separated from each other by adivider wall extending along a direction of airflow from the conduitsfrom the openings and beyond the openings.